At long last, the project is finished. Fresh off of the production line from Nacho Enterprises Railway System (NERS) are the long awaited tenders (and also power units) for the Mammoth Boy by jd davis.
This design underwent a few design changes, hence the delay. Here is the final product, worthy of such a monstrous locomotive.

Here is the first of the two tenders, which holds coal in the upper section and water below. This is standard amongst the newer "box" tender designs.

A top view of the tender, showing the massive holding area for the coal. Also shown is the IR Receiver.

The entire top section has been removed to show the bottom section, which also holds the two XL Motors.

A close-up of the XL Motors. The Technic pins are there so the motors do not fall out when the tender is picked up.

The side of the tender has been removed to show the "cage" that I referred to in an earlier creation to hold the motors in place. The motors are able to pivot about in this "cage" whenever the tender enters and exits a turn.

Part of the "cage" has been removed, showing more details.

A close-up of the front of the tender. Since the first tender is built in 9-wide and the trailing truck of the Mammoth Boy has its aft coupler lower than standard height, I was left scratching my head for a while trying to design something that would work. Well, it does now. The lead coupler of the first tender is separate from the truck, and is simply connected to a 2x2 plate with an inverted pin. Why are the simplest solutions so hard to come up with?

The rear end of the first tender. The coupler is part of the last truck, and as such sits at a standard height.

The second tender, which is simply a canteen (that means it holds only water) built in Vanderbilt style. It is based on my earlier Vanderbilt tender design. Once again, the canteen is built in an odd number wide (number unknown at the moment), so some modifications had to be made.

The top of the canteen. The IR Receiver sits underneath the hole on the top.

The top of the canteen removed. The top comes off as a single piece, which is odd for me since most of my designs have the removable top in several sections. However, the canteen design prompted for this.

Once again, the top section has been removed to show where the motors sit. There is also room in there somewhere for a Battery Box. So, the tenders each have two XL Motors, an IR Receiver, and a Battery Box. Which means that you will have to set each Receiver to the same channel. It also means that four motors will be a lot of hauling power. I saw a video of a locomotive that only had two motors in this configuration and it was easily pulling a lot of cars. How many, I cannot tell you. I lost count after twenty.

The front of the canteen. It definitely looks more cylindrical than my previous version, which is partly due to it being one stud wider. That makes the tender an 11-wide. That answers the previous question.

The rear end of the canteen, which sports lights that can fit Power Function Lights, and a combined ladder technique.

The Mammoth Boy, with her (or is it "his"? Clarification please) new tenders. What a grand sight to see.

A side view of the now completed locomotive. Even though each tender is six tracks in length, the Mammoth Boy still dwarfs both of them. That is insane, I tell you.

A rear angled shot of the Mammoth Boy. This is probably my favorite picture. Hold the jokes.

And your final parting shot of the majestic monstrosity that is the Mammoth Boy.

*Twitch's Remarks*
So, it is finally done. Back in December (I think?) jd davis asked me to power his Mammoth Boy, only because I asked how it was going to be motorized. He asked how I would do it, and thus I offered to create a solution. Through numerous delays (this thing called "work", being deployed, other projects, and making time for my wife) I was able to finish this. I am quite proud of how this turned out. Also, it SHOULD answer any questions on how my XL Motor Bogie/Truck design works and how it mounts. It practically just sits inside, not connected to anything (except the IR Receiver, but that does not really count). If this does not clear that up, I have no clue what will.
The basis of this design should work for anyone has a freight locomotive that needs massive hauling power. Keep in mind that with how the motor/bogies/trucks are made, your locomotive will not be a speed demon. It deals with gearing and science that I do not feel like explaining, but it is set at a 1:1 ratio. Let us keep it at that.
On a closing note, I have no NEW train projects at the moment. I will probably upload some others that have been put off or have already been featured (like the rest of the Christmas Train cars). However, I think that I will get back to building Mechas. I have had several ideas there for quite some time, but my train craze has kind of taken over recently. If anyone has any train-related requests that they would like to see from me or would like me to design, just let me know and I will see what I am able to come up with.

Quoting jd davis
im not wanting a complete failure I want a steam turbine that is like those two in the electric motor drive system.

OH! So I am taking a failed design (because practically none of them could opperate efficiently under 30 mph) and create a successful one? It is a good thing that I believe in Magic. Well, my wife does. She is a Disney nut. I guess it rubs off... Okay, time for a miracle.

Quoting jd davis
the solar generators and steam turbines are just for show the engine is like a electric loco which has no huge drivers just electric motors that drive regular sized wheels no drive rods involved. if you need to know what im talking about search for the Norfolk and western jawn henry and the c&o m1 turbines.

Alright, I will look into that for you. It figures, as SOON as I post a new Mech, you have to go do this and drag me back into train world... Oh no, oh the pain and agony of it all! Haha, I am just joking around.

the solar generators and steam turbines are just for show the engine is like a electric loco which has no huge drivers just electric motors that drive regular sized wheels no drive rods involved. if you need to know what im talking about search for the Norfolk and western jawn henry and the c&o m1 turbines.

Quoting jd davis
well hopefully the xl drivers give me the speed im wanting. after I get the electronics in the boiler and surrounding areas im going to work on the drive rods and pistons since the j1 has none at the moment. also if you don't mind, since you did a really great job with the mammoth, could you make a big bulky steam turbine for me? i want at least 5 of your solar generators that can work on turbine power and solar energy both as well as 5 steam turbines attached to the generators. there are no drivers like a traditional steamer. the cab is forward of the boiler which faces backwards with the stack at the back of the loco. you have free reign besides these things.

For drive rods, I would suggest going to zephyr's shop on Bricklink. He has some GREAT custom drive rods. I have not used them myself, but I have only read good things about them. For the solar generator that I created, it does not have any PF ability. So you are looking for a solar-powered cab-forward steam locomotive that has no drivers? Even though having drivers and driving rods are essential to a steam locomotive? I am confused, do you think that you could clarify a tad more of what you are looking for?

well hopefully the xl drivers give me the speed im wanting. after I get the electronics in the boiler and surrounding areas im going to work on the drive rods and pistons since the j1 has none at the moment. also if you don't mind, since you did a really great job with the mammoth, could you make a big bulky steam turbine for me? i want at least 5 of your solar generators that can work on turbine power and solar energy both as well as 5 steam turbines attached to the generators. there are no drivers like a traditional steamer. the cab is forward of the boiler which faces backwards with the stack at the back of the loco. you have free reign besides these things.

Quoting jd davis
yes im using 12 tooth bevels originally it was to be a 2:1 ratio from motor to drivers but the gears kept slipping so I went for the current ratio since the drivers do speed the engine up

I saw this design on flickr by Nathaniel Brill in his 4-8-8-4 Big Boy when I was researching the XL Motor design. He said that it could get good hauling power, but it was not as fast as he wanted. His Emerald Night with an XL Motor was *slightly* faster. Keep us posted with how this works out!

Quoting jd davis
the j1 is 9 and 3/4 tracks long including non powered tender. the engine is powered by 4 m motors installed in the boiler with a gear ratio of 1:1 with the xl drivers. also in side the engine is the battery box and soon to be ir receiver. in the smoke box is pf lights connected to the classification lampss and soon as I order them non lego lights for the mars and head lights.

Pretty nice! I look forward to it. I take it that you are using 12-tooth gears? I like how you are putting everything inside the locomotive. For extreme power I have found that a tender-powered locomotive works well. So I look forward to it!

the j1 is 9 and 3/4 tracks long including non powered tender. the engine is powered by 4 m motors installed in the boiler with a gear ratio of 1:1 with the xl drivers. also in side the engine is the battery box and soon to be ir receiver. in the smoke box is pf lights connected to the classification lampss and soon as I order them non lego lights for the mars and head lights.

Quoting jd davis
i'll see if when the j1 is done if I can get video and some pics of the real life engine it looks a lot different then the rarely updated ldd file. oh and imagine #10000 with smoke deflectors and streamlining.

I was about to reply to Trevor when I saw that jd also commented, so I "reply" to both. Trevor, unless I use this particular design in anything that I create, I will not post a video of this since I am not the one that this was made for. If jd davis creates this in real bricks, perhaps he will post a video of it. jd, how is the J1 going to be powered? And I did not think that the J1 is as big as the Mammoth Boy.

i'll see if when the j1 is done if I can get video and some pics of the real life engine it looks a lot different then the rarely updated ldd file. oh and imagine #10000 with smoke deflectors and streamlining.

Quoting cyberfrank 2010
the tenders are 3 baseplates long? I would have liked to see it in a turn,to check the reaction of the train, and how it looks, it s impossibly huge, I can t beleive someone would try this for real.

I cannot tell you the exact stud length of these because I never counted, but several 8x16 plates were used in their construction. Putting something in a turn in LDD is more of a pain than it is worth, hence why you will never see it from anyone. I have not seen anyone do it. I have no clue if jd davis will do this for real some day; but if he did, this is how I recommend to do it. But if this IS ever done in real bricks, I demand many pictures of it!

Quoting Trevor Young
I feel that this would need a VERY large turning radius to be usable as an actual model. Im assuming the 2 tenders are to be used at the same time. Very nice.

In "theory" they are designed to work on regular track, which includes curves and whatnot. Granted, there MAY (most likely will) be some under-hang. Yes, they are meant to be used at the same time. That large locomotive would look silly with only one of those. What did you think this locomotive was, the sole 2-8-8-8-4? Which was a complete failure, by the way.